Process for obtaining 1,1,1,2-tetrachloroethane

ABSTRACT

The process for producing 1,1,1,2-tetrachloroethane by chlorination of 1,1-dichloroethylene in the absence of light.

United States Patent Correia et al.

PROCESS FOR OBTAINING l ,1 ,1 ,2-TETRACHLOROETHANE Inventors: YvesCorreia; Jean-Claude Slrini,

both of Saint-Auban, France Assignee: Rhone-Progil, Courbevoie, FranceFiled: Mar. 17, 1972 Appl. No.: 235,777

Related US. Application Data Continuation of Ser, No, 786,740, Dec. 24,1968, abandoned.

Foreign Application Priority Data Dec 29, 1967 France 134294/67 US. Cl260/658 R Int. Cl. C076 17/04 Field of Search 260/658 R References CitedUNITED STATES PATENTS 11/1937 Cass 260/658 R FOREIGN PATENTS ORAPPLICATIONS 530,649 7/l93l Germany .4 260/658 R 606,33l 10/[960 Canada260/660 OTHER PUBLICATIONS Poutsma et al., JACS, 86, pp. 3,8073,814(l964).

Primary Examiner-Delbert E. Gantz Assistant Examiner.loseph A. BoskaABSTRACT The process for producing l,l,l,2-tetrachloroethane bychlorination of l,l-dichloroethylene in the absence of light.

3 Claims, No Drawings PROCESS FOR OBTAINING 1 ,1 ,1 ,Z-TETRACHLOROETHANEThis is a continuation of application Ser. No. 786.740 tiled Dec. 24.I968. now abandoned.

This invention relates to a process for the preparation ofl,l,l,Ltetrachloroethane by chlorination of l,ldichloroethylene.

It is well known that chlorination of l,ldichloroethylene. in thepresence of light, yields l,l,1,Z-tetrachloroethane in yields as high as90-9571 of theoretical. According to the publication of M. L. Poutsmaand R. L. Hinman, Journal of American Chemical Society, Vol. 86, page3807 M964), it is also known that in the absence of light and at atemperature of C. l,ldichloroethylene remains stable over a long periodof time and that it does not react with chloone.

This invention is based upon the unexpected discovery that chlorinationof l,l-dichloroethylene to form l,l,l ,2tetrachloroethane can be carriedout in the abscnce of light.

it is an object of this invention to produce and to pro vicle a methodfor producing l,l,l ,2tetrachloroethane by chlorination ofl,l-dichloroethylene in the absence of light.

In accordance with the practice of this invention, 1,1 dichloroethyleneis reacted in the liquid phase with molecular chlorine in a reactionzone, in the absence of catalyst and light and at a temperature withinthe range of 20 to 90 C and preferably within the range of 50 to 70 C.

By the term absence of catalyst." it is meant that if traces ofaluminum. iron. copper, titanium. antimony, sulphur and/or phosphorusare present. as in the form of their chlorides, either as impurities oras a result of corrosion of the production equipment, such traces shouldbe present in very small proportions below 0.004% by weight, expressedin the form of chlorides, based on the liquid reaction phase, andpreferably below 0.002570 by weight.

The dichloroethylene is employed in the liquid phase in accordance withthe practice of this invention and is reacted in solution in one or morehalogenated solvents, such as hexachlorobutadiene. and preferably l,l,l.Z-tetrachloroethane. it is beneficial to make use as the sol ent mediumof chlorinated compounds prepared by the process of this invention. Thedichloroethylene can be diluted or not by the solvent before beingintroduced into the reaction medium.

The molecular chlorine employed in the practice of this invention can bein the form of liquid chlorine, which is gasified before entering intothe reaction. or in the form of chlorine gas, such as collected at theexit of chlorine production plants.

it has been found that the yield of l,l ,l ,2- tetrachloroethane isrelatively insensitive to the purity of the chlorine whether use is madeof 99.9% pure liquid chlorine or 95% pure chlorine gas, in which themain impurities may be C6 0 N and CO.

Chlorine can be diluted by gases which do not react under the reactionconditions. such for example as the gases identified above asimpurities. Chlorine diluted by inert gases in a. molar ratio up to Hiis not detrimental to the reaction but generally it is disadvantageousto make use of excessive amounts of inert gas because of the added costof handling such larger volumes of gases and because of its detrimentaleffect on productivity.

The molar ratio of chlorine/l l-dichloroethylene should be equal to orless than 0.95 and, in order to achieve maximum productivity of theprocess, it is preferred to utilize a molar ratio within the range of0.8 to 0.9. However, the process of this invention can be carried outwith a molar ratio below 0.8 but the productivity falls off inproportion to the deviation below 0.8.

Applicants have found that, for obtaining a high selectivity andconsequently a high yield above 95%, for instance 98-99% ofunsymmetrical tetrachloroethane in a time suitable for commercialpractice, the starting l.l-dichloroethylene should be free orpractically free (below 0.001% by weight) of stabilizers usuallyincorporated into l,l-dichloroethylene, such as phenol orp-methoxyphenol, which stabiliizers should be eliminated before thechlorination reaction.

Furthermore, it has been established that the chlorination reaction ofl,l-dichloroethylene, in the absence ofa catalyst, takes place by wayofa radical mechanism as illustrated by the following equation:

The very small quantity of pentachloroethane, which can form, isobtained by direct substitution of l,l l ,2- tetrachloroethane. Thisexplains why the formation of trichloroethylene is unobserved. Theformation of l,l,l-trichloroethane is unobserved also sincehydrochlorination of l,l-dichloroethylene cannot occur in the absence ofcatalyst.

According to the invention, the residence time, of reactants in thereaction zone may vary within the range of 3 to 9 hours and preferablybelow 7 hours and the conversion of l,l-dichloroethylene is limited towithin the range of to molar percent.

The following examples are given by way of illustration, but not by wayof limitation, of the practice of this invention.

EXAMPLE 1 One hundred moles/hour of l,l-dichloroethylene (phenol below0.0002% by weight) of 99.5%- purity and 9l moles/hour of raw chlorine of97% purity are introduced continuously at a temperature of 50 to 55 Cand under atmospheric pressure into a reaction zone in the form ofanickel reactor, and in the absence of light radiations. The molar ratioof (l, /CO CH is 0.88.

The residence time of reactants in the reactor is 5 hours and thetransformation rate of l,l dichloroethylene at the end of this time islimited to 89 molar percent. A liquid effluent, which is collectedcontinuously from the reactor, is submitted to continuous distillation.The first running fractions, essentially composed ofl,l-dichloroethylene. are recycled to the reactor. The last runningfraction is composed essentially of l,l ,l ,Ltetrachloroethane. Theyield of l,l l ,2 tetrachloroethane, based upon the converted l,ldichloroethylene, is 98.5%. The main impurity is pentachloroethane,representing 0.7 molar percent.

By way of comparison, the chlorination reaction is carried out under theabove conditions but with a l.ldichloroethylene of 98.5% purity, theimpurity being phenol present in the amount of0.27 by weight. It will henoticed that chlorination does not take place due to the inhibitiveaction of the stabilizing agent on the chlorination ofl,l-dichloroethylene.

Likewise, by way of comparison, the chlorination reaction is carried outunder the same conditions as in Example 1, but with a nickel reactorequipped with a light radiation source. After 5 hours of residence timein the reactor, the conversion rate of the 1,1- dichloroethylene is 92.7molar per cent. A liquid effluent is collected continuously from thereactor and submitted to continuous distillation. The first runningfraction, essentially composed of l,l dichloroethylene. is recycled tothe reactor. The last running fraction is composed mainly ofl.1,1,2-tetrachloroethane accompanied with heavier chlorinatedimpurities. The yield of 1,1 ,1 ,Z-tetrachloroethane based upon theconverted 1,1is only 91.5% and the main impurity is composed of:

a mixture of heavy products (chlorinated C representing 6 molar percentexpressed in the form of 1,1-dichloroethylene pentachloroethane 2 molarpercent hexachloroethane 0.05 molar percent.

In another comparative test, the chlorination is carried out byintroducing at a temperature of 50 to 55 C, under atmospheric pressure,into the nickel reactor of Example 1, and in the absence of lightradiations, 100 moles/hour of 1,1-dichloroethylene (phenol below 0.0002%by weight) of 99.5% purity and 110 moles/- hour of raw chlorine gas of97% purity, obtained directly from electrolysis cells, the molar ratioof chlorine/l .l-dichloroethylene being 1.07. The residence time in thereactor is 5 hours and the conversion rate of 1,1-dichloroethylene is 98molar per cent. A liquid effluent is collected continuously from thereactor and submitted to continuous distillation. The first runningfractions are recycled to the reactor. The last running fraction iscomposed essentially of:

1,1,1.2-tetrachloroethane which is obtained only in a yield of 91.5%based on the 1,1-dichloroethylene converted pentachloroethane as mainimpurity representing 8 molar percent of 1,1-dichloroethylene converted.

In a comparative test, the chlorination of 1,1- dichloroethylene iscarried out under the same conditions as in Example 1 except that theresidence time in the reactor is 2.5 hours nd the conversion rate of1,1- dichloroethylene at the end of this time is limited to 70 molarpercent. A liquid effluent is collected continuously from the reactorand submitted to continuous distillation. The first running fractions,essentially composed of l,1dichloroethy1ene,are recycled to the reactor.The last running fraction is composed of l,1,l,2- tetrachloroethane. Theyield of 1,1,l,2- tetrachloroethane, based on the 1,1-dichloroethyleneconverted, is 98.5 molar per cent. The main impurity ispentachloroethane, representing 0.6 molar percent. However, due to thefact that a nonmegligible portion of the chlorine used does not react,but either remains dissolved in the reaction med um or escapes continuously from the reactor through the condenser. the productivity of 1,1,1.Z-tetrachloroethane remains far below that of Example 1.

EXAMPLE 2 One hundred moles/hour of 1,1-dichloroethylene (less than0.000192 by weight phenol) of 99.8% purity, 81 moles/hour of gasiliedliquid chlorine, and 0.170 g/hour of ferric chloride, corresponding to0.001% by weight FeCl based upon the reaction liquid phase, areintroduced continuously at a temperature of 45 to 50 C, underatmospheric pressure, into a glass lined steel reactor in the absence oflight radiations.

The residence time of the reactants in the reactor is 3.5 hours and theconversion rate of 1,1- dichloroethylene at the end of this time islimited to molar percent. A liquid effluent is continuously collectedfrom the reactor and submitted to distillation. The first runningfractions, essentially composed of 1.1-dichloroethylene, are recycled tothe reactor. The last running fraction is essentially composed of 1,1,1,2- tetrachloroethane and the yield, based upon the con verteddichloroethylene. is 99%, the main impurity being composed of 0.6 molarpercent of pentachloroethane.

In a comparative test, the chlorination of 1,1- dichloroethylene iscarried out under the same conditions as in Example 2 except that theferric chloride is introduced at a rate of 3.4 g/hour instead of 0.170g/hour, corresponding to 0.02% by weight FeCl based on the reactionliquid phase.

The conversion rate of 1,1-dichloroethylene, after a residence time of3.5 hours of reaction is 83 molar per cent. The liquid effluent whichflows continuously from the reactor has the following molar composition:

1,1,1 ,2-tetruchloroethanc 60 trichloroethylenc l6 pentuchloroethane 2 ll -trichloroethane 5 1,1-dichloroethylene 17 The yield oftetrachloroethane is only 72.3 molar percent based upon converted1,1-dichloroethylene.

EXAMPLE 3 Example 2 is repeated but the ferric chloride is replaced withthe same amount of nickel chloride.

The yield of 1,1,1,2-tetrachloroethane based upon the converted1,1-dichloroethylene is 99 molar percent.

It will be understood that changes may be made in the details offormulation and operation without departing from the spirit of theinvention, especially as defined in the following claims.

We claim:

1. A process for the preparation of 1,1 ,l,2- tetrachloroethanecomprising reacting 1,1- dichloroethylene in the liquid phase in thepresence of 1,1.1,2-tetrachloroethane with molecular chlorine at atemperature within the range of 2090C in the absence of light and in theabsence of a catalyst, wherein the molar ratio of chlorine to1,1dichloroethylene is within the range of 0.8 to 0.95 and wherein the1,1- dichloroethylene contains less than 0.001% by weight of astabilizer.

2. The process as claimed in claim 1 in which the reaction time iswithin the range of 3 to 9 hours and the conversion of1,1-dichloroethylene is limited to within the range of 80 to molarpercent.

3. The process as claimed in claim 1 in which the reaction is carriedout at a temperature within the range of 50 to 70 C.

1. A PROCESS FOR THE PREPARATION OF 1,1,1,2TETRACHLOROETHANE COMPRISINGREACTING 1,1-DICHLOROETHYLENE IN THE LIQUID PHASE IN THE PRESENCE OF1,1,1,2TETRACHLOROETHANE WITH MOLECULAR CHLORINE AT A TEMPERATURE WITHINTHE RANGE OF 20*-90*C IN THE ABSENCE OF LIGHT AND IN THE ABSENCE OF ACATALYST, WHEREIN THE MOLAR RATIO OF CHLORINE TO 1,1-DICHLOROETHYLENE ISWITHIN THE RANGE OF 0.8 TO 0.95 AND WHEREIN THE 1,1-DICHLOROETHYLENECONTAINS LESS THAN 0.001% BY WEIGHT OF STABILIZER.
 2. The process asclaimed in claim 1 in which the reaction time is within the range of 3to 9 hours and the conversion of 1,1-dichloroethylene is limited towithin the range of 80 to 95 molar percent.
 3. The process as claimed inclaim 1 in which the reaction is carried out at a temperature within therange of 50* to 70* C.